The overall goal of this continuation application is to develop dental amalgams which release significantly lower levels of mercury than current commercial amalgams. Our studies have suggested that the development of amalgams with gamma 1 (Ag-Hg) matrices containing large amounts of readily oxidized metals, such as tin and indium, should result in amalgams with significantly reduced mercury release. This reduction would result from the formation of an inhibiting surface oxide, as well as to a reduction in the vapor pressure of the mercury releasing phases of amalgam. The three specific aims are: #1) To develop a series of binary and ternary alloys containing mercury with varying concentrations of readily oxidized metals, i.e. indium, tin and zinc, which can be used as-the liquid phase for trituration with common dental amalgam alloy powders; #2) To fully characterize the properties of the amalgams produced from the most promising alloys developed in aim one; and #3) To explain the properties and mercury release characteristics for the most promising amalgams by examining their microstructure, matrix phase composition, and vapor pressure and thermal stability. To accomplish the aims, binary liquid alloys of mercury and indium and ternary liquid alloys of mercury, indium and tin or zinc, will be mixed with four different types of common dental amalgam alloy powders to produce amalgams. An initial screening of approximately 24 amalgams will be conducted by determining mercury vaporization during setting, and by comparing one-hour compressive strength, creep and dimensional change to the ANSI/ADA Specification #1 minimum values for amalgams. Formulations which pass the screening process will be fully characterized in specific aim #2 by quantitating mercury vaporization after abrasion, 1-day and 7-day compressive strength, flexural strength, working time and handling, corrosion resistance; dissolution of elements during static and dynamic corrosion, and cytotoxicity. Finally, a full evaluation of microstructure and phase analysis will be performed by scanning electron microprobe, limited surface analysis data will be collected by Auger spectroscopy, and thermalgravimetry and differential scanning calorimetry will be used to measure vapor pressure and thermal stability of the amalgams.